GMAT Sentence Correction (SC) | Re: Literacy opened up entire realms of verifiable knowledge to ordinary

I understand the B has the correct Pronoun antecedent. Now please explain this - isnt 'previously been considered' redundant? how is that correct? been considered should suffice, there is no need for 'previously'. Experts, please help; I would appreciate an early response.

Thanks a ton,
I know nothing

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